Creatinine Ratios in Random Sampled and 24-Hour Urines of White-Tailed Deer

We examined assumptions associated with collecting and chemically analyzing single urine specimens of northern ungulates to assess their physiological responses to changes in nutrition to validate this technique. We determined the degree to which creatinine ratios of 5 urinary characteristics (urea nitrogen [N], sodium, potassium, calcium, and phosphorus) in single urine specimens, voided at various times of the day, reliably represented their values in 24-hour urines. We used computer simulation to compare data from 24-hour urine pools and random samples of single urine specimens collected from 12 hand-reared, adult male white-tailed deer (Odocoileus virginianus). Eight and 4 deer were fed high and low nitrogen diets, respectively. Overall, urea N:creatinine and potassium:creatinine exhibited the greatest potential. Specifically, during 5-day spring trials, 90% of the samples of single urine specimens had mean urea N:creatinine values differing ≤19.7 and 12.3% from the mean 24-hour urine values of the high nitrogen and low nitrogen-fed groups. During the summer trials, the difference was ≤14.5 and 27.5% for the high and low nitrogen-fed groups. For potassium:creatinine ratios, 90% of mean values of samples of single urine specimens from the high nitrogen and low nitrogen-fed groups differed from mean 24-hour urine values by 9.3 and 16.0% during spring and by 11.9 and 12.4% during summer. Additional research should examine similar comparisons in deer fed submaintenance diets.